Crossbar switch with magnetic latching



July 25, 1967 P. M. GAUGAIN CROSSBAR SWITCH WITH MAGNETIC IJATCHING Filed Dec.

2 Sheets-Sheet l July 25, 1967 P. M. GAUGAIN 3,333,217

CROSSBAR SWITCH WITH MAGNETIC LATCHING Filed Dec. 9, 1964 Y 2 Sheets -Sheet 2 United States Patent 3,333,217 CROSSBAR SWITCH WITH MAGNETIC LATCHING Emile Paul Maurice Gaugain, Vanves, France, assignor to International Standard Electric Corporation, New York, N .Y., a corporation of Delaware Filed Dec. 9, 1964, Ser. No. 417,019 Claims priority, application France, Dec. 20, 1963,

950,046, Patent 1,390,265

3 Claims. (Cl. 335-113) ABSTRACT OF THE DISCLOSURE In this crossbar switch, each electrical contact consists in a wire or a flat spring embedded in the selecting bar and bearing a permanent magnet. Each bar is submitted to a motion of translation in one direction when its selection electro-magnet is energized and in the opposite direction when said electro-magnet is de-energized. The contact springs are so shaped that the two magnets of each crosspoint are in a same plane parallel to the planes of the bars and that, when both bars move under the control of their electro-magnets, the permanent magnets stick together, the contact springs touch and remain in contact. The contact is broken when only one bar moves under the control of its electro-magnets as the magnets slide along each other.

The present invention concerns crossbar multiselectors in which the simultaneous displacement of one row bar and one column bar closes one or more electrical contacts and holds them in position by magnetic latching.

Crossbar multiselectors, or crossbar switches, have been described in numerous publications, as, for instance, in the June 1954 issue of Electrical Communications, and their design and mode of realization are well known.

It will be recalled that such a switch has n'horizontal selecting bars and p vertical selecting bars which cross at right angles and which define np crosspoints. A stack of contacts is associated with each of these crosspoints in such a way that the contacts close when the horizontal bar and the vertical bar passing by this point are displaced successively, and that they remain closed when the horizontal bar resumes itsoriginal position.

Since the displacement of each bar is controlled by a selection electro-mag-net, contact is maintained by the electrical latching of the vertical selection electro-magnet.

Therefore, in such a switch, current flows through the winding of the vertical selection electro-magnet during the entire closing time of the contacts, and this can present disadvantages from the point of view of energy consumption. Moreover, the contact must be broken by an operation called dc-energizing, as soon as the connection which it established is no longer needed, at the end of a telephone communication, for instance;

In the present invention, each selecting bar is submitted to a motion of translation under the control of its electromagnet and the electrical contacts are made up of contact springs or of flat springs attached to the bar by one of their ends. Each of the springs bears a permanent magnet which ensures the magnetic latching of a crosspoint whose two bars have been energized.

Moreover, the different methods of multiselector realization according to this invention permit the use of much smaller and lighter devices than those previously known in the art.

According to this invention, a multiselector operates in the following way:

(1) The displacement of single select bar does not provoke the closing of any contact nor any temporary short-circuit;

(2) The simultaneous displacement of the two orthogonal selecting bars defining a crosspoint closes the contact or contacts connected to said crosspoint and their magnetic latching when, the electro-magnets being no longer energized, and the bars resume their original position; I V

(3) The unlatching and opening of contacts are obtained by the displacement of only one of the bars connected to the crosspoint.

This invention has therefore the object of realizing a crossbar multiselector wherein the contacts are held closed by magnetic latching.

Another object of the invention consists in realizing a multiselector of reduced size and weight.

BIG. 1 represents a crosspoint equipped with contact springs.

FIGS. 2.1, 2.2 and 2.3 show projections of the contact springs and of their magnets in the median plane for various positions of the selecting bars.

FIGS. 3.1 and 3.2 show a particular mode of realization of spring wires.

FIG. 4 shows the crosspoint equipped with fiat springs.

FIG. 1 represents, in a perspective view, the region of space relative to a'crosspoint defined in relation to the system of rectangular coordinates 0 x, 0 y, 0 2,. The two selecting bars passing by this point will be called, respectively: column bar and row bar.

A selection (not shown) associated with each bar imparts a translation movement to said bar when it is energized. When this electro-magnet is dc-energized, the bar returns to its original position, or rest position under the action of a return spring (not shown). Thus, the column bar is displaced along the axis 0 y in the direction of arrow V' when its electro-magnet is energized. A spring wire A E C F G rigidly fastened to this bar at point A, carries, on its part E 0 a permanent magnet M whose poles are referred to as N and S. Similarly, the row bar moves along the axis 0 x, in the direction of arrow H, and carries a spring wire A E C F G to which a permanent magnet M is fastened. The magnets are fastened to the springs by means, for example, of an insulating moulded part which encloses these two elements.

In order to simplify the figure, neither the electro- I magnets or the return springs of the two bars have been shown.

We will designate by:

M-the distance 0 0 between the two bars, measured on their common perpendicular;

I--the middle point of the segment 0 0 dthe distances O A and 0 A presumed equal, these distances being measured when the bars are in rest position;

Median plane-the plane passing through point I parallel to plane xO y; this plane intersects the planes xO z and yO z, along the lines IxO and IyO; T

v and h-the springs connected respectively to the column bars and the row bars;

fl-the angle of parts A E and A E of the springs v and h with respect to the plane x0 ath6 angle of the part A E of the spring v (of the part A E of the spring h) with respect to the plane yO z iz);

ethe distance separating the facing sides of the magnets M and M when the bars are in rest position.

Each of the springs, whose position at the embedding point is defined by the angles a and B, is bent in three points referenced, for the spring v for instance, C B

and F The bending at E is such that the magnet M is placed in the median plane and that its greatest dimension is parallel to the bissectrix ID, of the angle yOIxO. The bendings at C and F are such that the part E G of the spring remains in the median phase and the part F G of this spring comes in contact with the homologous part F G of the spring h when the electro-magnets of the two bars are simultaneously energized, the contact line being merged with the bissectrix 1D,.

The magnets M and M are fastened to the springs v and h in such a way that, at each crosspoint, the poles which face each other are of opposite polarity.

Since the bars in FIG. 1 are shown in rest position, the elasticity of the springs and the strength of the magnets are chosen such that the latter do not stick together and remain separated by a distance 2.

The mode of operation of the device of FIG. 1 will now be studied in relation to FIGS. 2.1, 2.2 and 2.3. These figures show, for various positions of the selecting bars, the projection of the springs and of their magnets in the median plane.

FIG. 2.1 represents this projection when none of the electro-magnets is energized and thus corresponds to FIG. 1.

FIG. 2.2 represents this projection when the electromagnet connected to the bar V is energized.

FIG. 2.3 represents this projection when the two electromagnets are energized simultaneously (parts A E and A 13 of the springs represented by unbroken line) and released simultaneously (parts A E and A E of the springs represented by dotted line).

When one of the electro-magnets is energized, the one connected to bar V, for instance (see FIG. 2.2), this bar moves a distance 1 towards point and it is seen that, when it comes to stop, the distance between the poles of same name on the magnets M and M has decreased and that these magnets tend to repel each other. During this movement, the part F G of the spring v moves paral- "lel to itself and approaches the bissectrix ID It cannot touch the part F G of the spring h if l e 2.

When the two selection electro-magnets are simultaneously energized, the magnets M and M stick to each other (see FIG. 2.3, parts A E and A E of springs v and h drawn in unbroken line) and the parts F G and F G of the springs touch each other, establishing contact if When the two selection electro-magnets are then simultaneously released, the magnets remain stuck together and the parts A E and A E of the springs become deformed, taking the positions shown in broken lines in FIG. 2.3. Contact is thus maintained by magnetic latching.

To cut off the contact, only one of the electro-magnets is energized, that connected to bar V, for instance. The magnet M then slips along the magnet M as the component of the magnetic field in the direction of the bissectrix is very weak and this contact is cut oil so that we get the position shown in FIG. 2.2. When this electromagnet is de-energized, we get the position shown in FIGS. 1 and 2.1.

All contact springs embedded on the same bar are multiplexed on a connection conductor so that, when contact is made between a spring v and a spring h, a connection is made between the connection conductors to which these springs are connected.

One has just described a method of realizing a crossbar multiselector with magnetic latching which has one pair of contacts moving in the median plane xOIyO. It is conceivable that one can realize, within the framework of the invention, multiselectors having several pairs of contacts per crosspoint, by placing the embedding points of the contacts on the vertical lines A A' and A A' (see FIG. 1) while still using only two magnets M and M per crosspoint.

We have just described, in relation to FIGS. 1 and 2, a mode of realization in which parts E G and E G of wires 11' and h are all placed in the median plane.

Numerous alternatives of execution of the contacts are conceivable in which the active parts are placed outside this plane, with a point contact instead of a linear one.

FIGS. 3.1 and 3.2 thus by way of a non-limitative example a mode of realization of the contacts in which a point contact takes place on the bissectrix ID, of the angle xOIyO.

FIG. 3.1 shows the projection of the springs and of their magnets on the median plane and FIG. 3.2 shows the projection of these elements on a vertical plane z'A' xO containing the part C G of the spring v and the segment A A as defined in FIG. 1.

Referring to FIG. 3.1, it is seen that the projections of the extremities G and G of the two springs do not cross, in rest position, the bissectrix ID Referring now to FIG. 3.2, it is seen that the end of a spring, the end C F G of spring v, for instance, is bent in the form of a V and that the points F and G are placed symmetrically with respect to the median plane. Thus it is seen that the springs v and it touch, on the bissectrix ID only when the two electro-magnets are energized simultaneously.

One can also realize multiselectors having several pairs of contacts in which the active parts of the springs are placed, as in this example, outside the median plane. The embedding points of the contacts on the verticals A A and A A' (FIG. 1) must then be spaced in such a way that the springs belonging to adjacent pairs of contacts do not touch during the displacement of only one of the bars.

It is also possible to realize a magnetic latching multiselector operating according to the principle described in relation with FIGS. 1 and 2 but wherein the contacts are constituted of flat springs.

FIG. 4 shows, in perspective view, the elements of a crosspoint equipped with flat springs. In this figure, the axes of coordinates and the contacts have the same references as in FIG 1.

Considering the fiat spring A I E G it is seen that it can be defined in the following way:

(1) It is right-angled at point I; and bent at point E (2) It is embedded on bar V at point A in such a way that its plane is parallel to plane xO z;

(3) The right angle at I is such that the plane of part J E of the flat spring is parallel to the plane x0 2 and that the median plane constitutes its longitudinal symmetry axis.

(4) The bend at E is such that the plane of part E G of the flat spring is parallel to the bissectrix plane (vertical plane containing the bissectrix ID and that its longitudinal axis is in the median plane.

It is easily verified that the operation of this multiselector is identical to that described in relation with FIG. 1, the contact being established, when the two electro-magnets are energized simultaneously, by the buttons P and P While the principles of the above invention have been described in connection with specificembodiments and particular modifications thereof it is to be clearly understood that this description is made by way of example and not as a limitation of the scope of the invention.

What I claim is:

1. A crossbar multiselector including a row selecting bar and a column selecting bar, each bar lying in a separate horizontal plane, each bar having a direction of motion along an axis perpendicular to that of the other bar, a crosspoint defined bysaid bars, electrical contact means including a pair of electrical contacts which close in response to simultaneous displacement of the row bar and the column bar associated with the crosspoint, magnetic means associated with each electrical contact for holding said electrical contacts closed by magnetic latching action in response to simultaneous displacement of' each selecting bar, said magnetic means releasing said electrical contacts in response to displacement of only one selecting bar.

2. A crossbar multiselector according to claim- 1 in which the electrical contact means include a contact spring embedded in each bar at a distance d from a perpendicular common to the two bars associated with a given crosspoint, the embedding point being placed so that said distance a' decreases when a bar is displaced in the direction to close said contacts and the magnetic latchingmeans include a permanent magnet attached to each contact spring, said spring being so bent that, first the magnet lies in a plane placed at the half-distance between the two horizontal planes, and second, the parallel sides of the two magnets attached to the springs pertaining to a crosspoint are separated by such a distance that they do no react upon each other, the facing magnetic poles being of opposite names.

References Cited UNITED STATES PATENTS 1,567,532 1'2/1925 Marburg 335-410 X FOREIGN PATENTS 1,188,224 3/1965 Germany.

BERNARD A. GILHEANY Primary Examiner.

R. N. ENVALL, JR., Assistant Examiner. 

1. A CROSSBAR MULTISELECTOR INCLUDING A ROW SELECTING BAR AND A COLUMN SELECTING BAR, EACH BAR LYING IN A SEPARATE HORIZONTAL PLANE, EACH BAR HAVING A DIRECTION OF MOTION ALONG AN AXIS PERPENDICULAR TO THAT OF THE OTHER BAR, A CROSSPOINT DEFINED BY SAID BARS, ELECTRICAL CONTACT MEANS INCLUDING A PAIR OF ELECTRICAL CONTACTS WITH CLOSE IN RESPONSE TO SIMULTANEOUS DISPLACEMENT OF THE ROW BAR AND THE COLUMN BAR ASSOCIATED WITH THE CROSSPOINT, MAGNETIC MEANS ASSOCIATED WITH EACH ELECTRICAL CONTACT FOR HOLDING SAID ELECTRICAL CONTACTS CLOSED BY MAGNETIC LATCH- 